This invention relates generally to the field of telephony, and more particularly to an improved protector module intended for use as a replacement in conjunction with older type protector blocks.
In recent years, owing to substantial improvement in the quality and availability of small gas filled tubes, practically all new installations are provided with gas tube type protection. For the most part, such modules are encased within a housing having connecting pins or contacts at one end thereof for engagement with corresponding terminals on a newer type protector block, there being a single such module for each subscriber pair.
There are, however, a great number of telephone offices still in operation which use protector blocks or an earlier design originally equipped with carbon block type protectors. Typical of such installations are the Western Electric Type C-50, the 3800 series, and Type 675 and 676 blocks, which are characterized in the provision of individual spring fingers, pairs of which resiliently grip the carbon block assembly which is slidably engaged between adjacent fingers. The carbon blocks provide an air gap performing the same function as a gas tube, but with the disadvantages inherent with this type of protection, such as the deterioriation of the surfaces of the blocks forming the air gap. Replacement modules for this type installation are already known in the art, and normally comprise all of the elements of the known gas tube modules, including not only the gas tube itself, and a meltable solder pellet, but a resilient element which becomes operative upon the melting of a solder pellet which causes a shorting of the gas tube should it fail during a sustained excess current surge. No attempt has been made to simplify the construction of such modules by utilizing the resilient force available in the spring fingers which retain the module in installed position.